1 //===-- RISCVMCExpr.cpp - RISCV specific MC expression classes ------------===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 //
9 // This file contains the implementation of the assembly expression modifiers
10 // accepted by the RISCV architecture (e.g. ":lo12:", ":gottprel_g1:", ...).
11 //
12 //===----------------------------------------------------------------------===//
13
14 #include "RISCVMCExpr.h"
15 #include "MCTargetDesc/RISCVAsmBackend.h"
16 #include "RISCVFixupKinds.h"
17 #include "llvm/BinaryFormat/ELF.h"
18 #include "llvm/MC/MCAsmLayout.h"
19 #include "llvm/MC/MCAssembler.h"
20 #include "llvm/MC/MCContext.h"
21 #include "llvm/MC/MCStreamer.h"
22 #include "llvm/MC/MCSymbolELF.h"
23 #include "llvm/MC/MCValue.h"
24 #include "llvm/Support/ErrorHandling.h"
25
26 using namespace llvm;
27
28 #define DEBUG_TYPE "riscvmcexpr"
29
create(const MCExpr * Expr,VariantKind Kind,MCContext & Ctx)30 const RISCVMCExpr *RISCVMCExpr::create(const MCExpr *Expr, VariantKind Kind,
31 MCContext &Ctx) {
32 return new (Ctx) RISCVMCExpr(Expr, Kind);
33 }
34
printImpl(raw_ostream & OS,const MCAsmInfo * MAI) const35 void RISCVMCExpr::printImpl(raw_ostream &OS, const MCAsmInfo *MAI) const {
36 VariantKind Kind = getKind();
37 bool HasVariant = ((Kind != VK_RISCV_None) && (Kind != VK_RISCV_CALL) &&
38 (Kind != VK_RISCV_CALL_PLT));
39
40 if (HasVariant)
41 OS << '%' << getVariantKindName(getKind()) << '(';
42 Expr->print(OS, MAI);
43 if (Kind == VK_RISCV_CALL_PLT)
44 OS << "@plt";
45 if (HasVariant)
46 OS << ')';
47 }
48
getPCRelHiFixup(const MCFragment ** DFOut) const49 const MCFixup *RISCVMCExpr::getPCRelHiFixup(const MCFragment **DFOut) const {
50 MCValue AUIPCLoc;
51 if (!getSubExpr()->evaluateAsRelocatable(AUIPCLoc, nullptr, nullptr))
52 return nullptr;
53
54 const MCSymbolRefExpr *AUIPCSRE = AUIPCLoc.getSymA();
55 if (!AUIPCSRE)
56 return nullptr;
57
58 const MCSymbol *AUIPCSymbol = &AUIPCSRE->getSymbol();
59 const auto *DF = dyn_cast_or_null<MCDataFragment>(AUIPCSymbol->getFragment());
60
61 if (!DF)
62 return nullptr;
63
64 uint64_t Offset = AUIPCSymbol->getOffset();
65 if (DF->getContents().size() == Offset) {
66 DF = dyn_cast_or_null<MCDataFragment>(DF->getNextNode());
67 if (!DF)
68 return nullptr;
69 Offset = 0;
70 }
71
72 for (const MCFixup &F : DF->getFixups()) {
73 if (F.getOffset() != Offset)
74 continue;
75
76 switch ((unsigned)F.getKind()) {
77 default:
78 continue;
79 case RISCV::fixup_riscv_got_hi20:
80 case RISCV::fixup_riscv_tls_got_hi20:
81 case RISCV::fixup_riscv_tls_gd_hi20:
82 case RISCV::fixup_riscv_pcrel_hi20:
83 if (DFOut)
84 *DFOut = DF;
85 return &F;
86 }
87 }
88
89 return nullptr;
90 }
91
evaluateAsRelocatableImpl(MCValue & Res,const MCAsmLayout * Layout,const MCFixup * Fixup) const92 bool RISCVMCExpr::evaluateAsRelocatableImpl(MCValue &Res,
93 const MCAsmLayout *Layout,
94 const MCFixup *Fixup) const {
95 if (!getSubExpr()->evaluateAsRelocatable(Res, Layout, Fixup))
96 return false;
97
98 // Some custom fixup types are not valid with symbol difference expressions
99 if (Res.getSymA() && Res.getSymB()) {
100 switch (getKind()) {
101 default:
102 return true;
103 case VK_RISCV_LO:
104 case VK_RISCV_HI:
105 case VK_RISCV_PCREL_LO:
106 case VK_RISCV_PCREL_HI:
107 case VK_RISCV_GOT_HI:
108 case VK_RISCV_TPREL_LO:
109 case VK_RISCV_TPREL_HI:
110 case VK_RISCV_TPREL_ADD:
111 case VK_RISCV_TLS_GOT_HI:
112 case VK_RISCV_TLS_GD_HI:
113 return false;
114 }
115 }
116
117 return true;
118 }
119
visitUsedExpr(MCStreamer & Streamer) const120 void RISCVMCExpr::visitUsedExpr(MCStreamer &Streamer) const {
121 Streamer.visitUsedExpr(*getSubExpr());
122 }
123
getVariantKindForName(StringRef name)124 RISCVMCExpr::VariantKind RISCVMCExpr::getVariantKindForName(StringRef name) {
125 return StringSwitch<RISCVMCExpr::VariantKind>(name)
126 .Case("lo", VK_RISCV_LO)
127 .Case("hi", VK_RISCV_HI)
128 .Case("pcrel_lo", VK_RISCV_PCREL_LO)
129 .Case("pcrel_hi", VK_RISCV_PCREL_HI)
130 .Case("got_pcrel_hi", VK_RISCV_GOT_HI)
131 .Case("tprel_lo", VK_RISCV_TPREL_LO)
132 .Case("tprel_hi", VK_RISCV_TPREL_HI)
133 .Case("tprel_add", VK_RISCV_TPREL_ADD)
134 .Case("tls_ie_pcrel_hi", VK_RISCV_TLS_GOT_HI)
135 .Case("tls_gd_pcrel_hi", VK_RISCV_TLS_GD_HI)
136 .Default(VK_RISCV_Invalid);
137 }
138
getVariantKindName(VariantKind Kind)139 StringRef RISCVMCExpr::getVariantKindName(VariantKind Kind) {
140 switch (Kind) {
141 case VK_RISCV_Invalid:
142 case VK_RISCV_None:
143 llvm_unreachable("Invalid ELF symbol kind");
144 case VK_RISCV_LO:
145 return "lo";
146 case VK_RISCV_HI:
147 return "hi";
148 case VK_RISCV_PCREL_LO:
149 return "pcrel_lo";
150 case VK_RISCV_PCREL_HI:
151 return "pcrel_hi";
152 case VK_RISCV_GOT_HI:
153 return "got_pcrel_hi";
154 case VK_RISCV_TPREL_LO:
155 return "tprel_lo";
156 case VK_RISCV_TPREL_HI:
157 return "tprel_hi";
158 case VK_RISCV_TPREL_ADD:
159 return "tprel_add";
160 case VK_RISCV_TLS_GOT_HI:
161 return "tls_ie_pcrel_hi";
162 case VK_RISCV_TLS_GD_HI:
163 return "tls_gd_pcrel_hi";
164 case VK_RISCV_CALL:
165 return "call";
166 case VK_RISCV_CALL_PLT:
167 return "call_plt";
168 case VK_RISCV_32_PCREL:
169 return "32_pcrel";
170 }
171 llvm_unreachable("Invalid ELF symbol kind");
172 }
173
fixELFSymbolsInTLSFixupsImpl(const MCExpr * Expr,MCAssembler & Asm)174 static void fixELFSymbolsInTLSFixupsImpl(const MCExpr *Expr, MCAssembler &Asm) {
175 switch (Expr->getKind()) {
176 case MCExpr::Target:
177 llvm_unreachable("Can't handle nested target expression");
178 break;
179 case MCExpr::Constant:
180 break;
181
182 case MCExpr::Binary: {
183 const MCBinaryExpr *BE = cast<MCBinaryExpr>(Expr);
184 fixELFSymbolsInTLSFixupsImpl(BE->getLHS(), Asm);
185 fixELFSymbolsInTLSFixupsImpl(BE->getRHS(), Asm);
186 break;
187 }
188
189 case MCExpr::SymbolRef: {
190 // We're known to be under a TLS fixup, so any symbol should be
191 // modified. There should be only one.
192 const MCSymbolRefExpr &SymRef = *cast<MCSymbolRefExpr>(Expr);
193 cast<MCSymbolELF>(SymRef.getSymbol()).setType(ELF::STT_TLS);
194 break;
195 }
196
197 case MCExpr::Unary:
198 fixELFSymbolsInTLSFixupsImpl(cast<MCUnaryExpr>(Expr)->getSubExpr(), Asm);
199 break;
200 }
201 }
202
fixELFSymbolsInTLSFixups(MCAssembler & Asm) const203 void RISCVMCExpr::fixELFSymbolsInTLSFixups(MCAssembler &Asm) const {
204 switch (getKind()) {
205 default:
206 return;
207 case VK_RISCV_TPREL_HI:
208 case VK_RISCV_TLS_GOT_HI:
209 case VK_RISCV_TLS_GD_HI:
210 break;
211 }
212
213 fixELFSymbolsInTLSFixupsImpl(getSubExpr(), Asm);
214 }
215
evaluateAsConstant(int64_t & Res) const216 bool RISCVMCExpr::evaluateAsConstant(int64_t &Res) const {
217 MCValue Value;
218
219 if (Kind == VK_RISCV_PCREL_HI || Kind == VK_RISCV_PCREL_LO ||
220 Kind == VK_RISCV_GOT_HI || Kind == VK_RISCV_TPREL_HI ||
221 Kind == VK_RISCV_TPREL_LO || Kind == VK_RISCV_TPREL_ADD ||
222 Kind == VK_RISCV_TLS_GOT_HI || Kind == VK_RISCV_TLS_GD_HI ||
223 Kind == VK_RISCV_CALL || Kind == VK_RISCV_CALL_PLT)
224 return false;
225
226 if (!getSubExpr()->evaluateAsRelocatable(Value, nullptr, nullptr))
227 return false;
228
229 if (!Value.isAbsolute())
230 return false;
231
232 Res = evaluateAsInt64(Value.getConstant());
233 return true;
234 }
235
evaluateAsInt64(int64_t Value) const236 int64_t RISCVMCExpr::evaluateAsInt64(int64_t Value) const {
237 switch (Kind) {
238 default:
239 llvm_unreachable("Invalid kind");
240 case VK_RISCV_LO:
241 return SignExtend64<12>(Value);
242 case VK_RISCV_HI:
243 // Add 1 if bit 11 is 1, to compensate for low 12 bits being negative.
244 return ((Value + 0x800) >> 12) & 0xfffff;
245 }
246 }
247